Display device and manufacturing method thereof

ABSTRACT

A display device includes a bending area at which the display device is bendable; an organic light emitting element disposed on the substrate; an encapsulation layer covering an upper surface and a side surface of the organic light emitting element; and a bending area protection layer covering the bending area of the substrate. The upper surface of the encapsulation layer includes a nano structure defined by nano sized protrusions and depressions of the upper surface, and along the substrate, and the bending area is disposed separated from the encapsulation layer.

This application is a continuation application of U.S. patentapplication Ser. No. 17/019,458 filed on Sep. 14, 2020, which is adivisional application of U.S. patent application Ser. No. 16/509,614filed on Jul. 12, 2019 and issued as U.S. Pat. No. 10,818,873 on Oct.27, 2020, which claims priority to Korean Patent Application No.10-2018-0121115 filed on Oct. 11, 2018, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the entire contents of which areincorporated herein by reference.

BACKGROUND (a) Field

The present disclosure relates to a display device and a manufacturingmethod thereof.

(b) Description of the Related Art

Flexible display devices have been developed that use substrates thatare lightweight, strong against impact, and easily flexible. Flexibledisplay devices are attracting attention as next generation displaydevices that can be used for portable devices and wearable devices aswell as television (“TV”) and computer monitors.

In addition, when using the flexible substrates, an end portion of adisplay panel in which pads are located can be bent, thereby reducing adead space and a bezel width.

SUMMARY

Exemplary embodiments of the invention provide a display device and amanufacturing method thereof for reducing or effectively preventingdamage to the display device generated in a manufacturing process,simplifying the manufacturing process, and reducing a material cost,thereby improving productivity and yield for the manufactured displaydevice.

A display device according to an exemplary embodiment includes: asubstrate including a bending area; an organic light emitting elementdisposed on the substrate; an encapsulation layer covering an uppersurface and a side surface of the organic light emitting element; and abending area protection layer covering the bending area of thesubstrate. The upper surface of the encapsulation layer includes a nanostructure defined by nano sized protrusions and depressions of the uppersurface, and the bending area protection layer is disposed separatedfrom the encapsulation layer along the substrate.

The bending area protection layer may include a cured portion of anultraviolet ray curable material.

The ultraviolet ray curable material may include at least one among anacrylate-based polymer, polyurethane, and an acrylate-based materialincluding SiO.

The ultraviolet ray curable material may include at least one among anacryl-based resin, a butyl rubber, a vinyl acetate resin, an ethylenevinyl acetate (“EVA”) resin, a natural rubber, a nitrile, a siliceousresin, a silicon rubber, and a styrene block polymer.

Adhesiveness of the bending area protection layer may be about 50grams-force per inch (gf/inch) to about 200 gf/inch.

A maximum thickness of the bending area protection layer may be about 50micrometers (μm) to about 150 μm.

A supporting member disposed on a rear surface of the substrate may befurther included, and the supporting member may define an openingoverlapping the bending area.

Along the substrate, the supporting member defining the opening whichoverlaps the bending area, may overlap the bending area protection layercovering the bending area, by about 100 μm to about 200 μm.

A driving integrated circuit chip may be further included, and along thesubstrate, the bending area protection layer may be disposed separatedfrom the driving integrated circuit chip.

An upper protection layer removably attachable to the encapsulationlayer, a polarization film disposed on the upper surface of theencapsulation layer, and a window panel disposed on the polarizationfilm, may be further included.

Removal of the upper protection layer from the encapsulation layer maydispose an upper surface of the encapsulation layer exposed to outsidethe encapsulation layer, and form the nano structure.

The nano structure may form one closed line shape extended along edgesof the encapsulation layer.

At the bending area of the substrate, an adhesive supporting layerdisposed between the substrate and the bending area protection layer maybe further included.

The adhesive supporting layer may include at least one among anacryl-based resin, a butyl rubber, a vinyl acetate resin, an ethylenevinyl acetate (“EVA”) resin, a natural rubber, a nitrile, a siliceousresin, a silicon rubber, and a styrene block polymer.

The adhesiveness of the adhesive supporting layer may be higher than theadhesiveness of the bending area protection layer.

A manufacturing method of a display device according to an exemplaryembodiment includes: providing a substrate including a bending area atwhich the display device is bendable; providing an encapsulation layercovering each of an upper surface and a side surface of the organiclight emitting element, on the substrate; providing both an upperprotection layer on the encapsulation layer covering each of the uppersurface and the side surface of the organic light emitting element and abending area protection layer on the bending area of the substrate; andremoving the upper protection layer from the encapsulation layercovering each of the upper surface and the side surface of the organiclight emitting element. The providing both the upper protection layerand the bending area protection layer includes respectively applying anultraviolet ray curable material to the encapsulation layer and to thebending area of the substrate and curing the ultraviolet (“UV”) raycurable material, to form the upper protection layer and the bendingarea protection layer spaced apart from each other along the substrate.

The UV ray curable resin may include at least one among anacrylate-based polymer, polyurethane, and an acrylate-based materialincluding SiO.

The providing both the upper protection layer and the bending areaprotection layer may provide, the upper protection layer having amaximum thickness of about 100 μm to about 150 μm, and the bending areaprotection layer having a maximum thickness of about 50 μm to about 150μm.

The providing the upper protection layer may include providing anindividual layer of the ultraviolet ray curable material having athickness of about 10 micrometers to about 20 micrometers and curing theindividual layer, multiple times, to provide the upper protection layerhaving the maximum thickness of about 100 micrometers to about 150micrometers.

Forming an adhesive supporting layer which is between the substrate andthe upper protection layer and with which the substrate is attached tothe upper protection layer may be further included.

The adhesive supporting layer may include at least one among anacryl-based resin, a butyl rubber, a vinyl acetate resin, an ethylenevinyl acetate (“EVA”) resin, a natural rubber, a nitrile, a siliceousresin, a silicon rubber, and a styrene block polymer.

According to the exemplary embodiments, damage to a display device whichmay occur during a manufacturing process may be reduced or effectivelyprevented, the manufacturing process may be simplified and material costmay be reduced, thereby improving productivity yield of the manufactureddisplay device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages and features of this disclosure willbecome more apparent by describing in further detail exemplaryembodiments thereof with reference to the accompanying drawings, inwhich:

FIG. 1 is a top plan view of an exemplary embodiment of a displaydevice.

FIG. 2 is a cross-sectional view of the display device of FIG. 1 takenalong line II-II in FIG. 1 .

FIG. 3 is a flowchart showing an exemplary embodiment of a manufacturingmethod of a display device.

FIG. 4 is a cross-sectional view of an exemplary embodiment of a displaydevice which is unbent, provided according to the manufacturing methodof FIG. 3 .

FIG. 5 is a cross-sectional view showing the display device of FIG. 4which is bent.

FIG. 6 is a top plan view showing an exemplary embodiment of an uppersurface of an encapsulation layer of a display device.

FIG. 7 and FIG. 8 are cross-sectional views of modified exemplaryembodiments of a display device.

FIG. 9 is an image of an exemplary embodiment of an upper protectionlayer on an encapsulation layer of a display device.

DETAILED DESCRIPTION

The invention will be described more fully hereinafter with reference tothe accompanying drawings, in which exemplary embodiments are shown. Asthose skilled in the art would realize, the described embodiments may bemodified in various different ways, all without departing from thespirit or scope of the invention.

In order to clearly explain the invention, portions that are notdirectly related to the invention are omitted, and the same referencenumerals are attached to the same or similar constituent elementsthrough the entire specification.

In addition, the size and thickness of each configuration shown in thedrawings are arbitrarily shown for better understanding and ease ofdescription, but the invention is not limited thereto. In the drawings,the thicknesses of layers, films, panels, regions, etc., are exaggeratedfor clarity. In the drawings, for better understanding and ease ofdescription, the thicknesses of some layers and areas are exaggerated.

It will be understood that when an element such as a layer, film,region, or substrate is referred to as being related to another elementsuch as being “on” another element, it can be directly on the otherelement or intervening elements may also be present. In contrast, whenan element is referred to as being related to another element such asbeing “directly on” another element, there are no intervening elementspresent.

Further, in the specification, the word “on” or “above” means positionedon or below the object portion, and does not necessarily mean positionedon the upper side of the object portion based on a gravitationaldirection. Relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother element as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms, including “at least one,” unless the content clearly indicatesotherwise. “At least one” is not to be construed as limiting “a” or“an.” “or” means “and/or.” As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.In addition, unless explicitly described to the contrary, the word“comprise” and variations such as “comprises” or “comprising” will beunderstood to imply the inclusion of stated elements but not theexclusion of any other elements.

Further, in this specification, the phrase “on a plane” or “a top planview” means viewing a target portion from the top, and the phrase “on across-section” means viewing a cross-section formed by verticallycutting a target portion from the side.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). For example, “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10% or 5% of the stated value.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

A display device according to an exemplary embodiment is described withreference to FIG. 1 and FIG. 2 .

FIG. 1 is a top plan view of an exemplary embodiment of a displaydevice. FIG. 2 is a cross-sectional view of the display device of FIG. 1taken along line II-II in FIG. 1 .

Referring to FIG. 1 , the display device includes a display panel 100.The display device may be an organic light emitting diode display, aliquid crystal display, or an electrophoretic display. An exemplaryembodiment in which the display device is the organic light emittingdiode display is described below as an example.

The display panel 100 includes a display area DA at which an image isdisplayed and a non-display area PA at which an image is not displayed.The display area DA includes a pixel PX provided in plurality, the pixelPX being a region where an image is displayed. In the display area DA, aplurality of signal lines including a gate line 131 provided inplurality, a data line 132 provided in plurality, and a driving voltageline 133 provided in plurality are disposed or formed. Each pixel PXincludes a pixel circuit connected to a plurality of signal lines, andan organic light emitting element of which light emission is controlledby the pixel circuit. The non-display area PA is a region where elementsor wiring for generating and transmitting various signals applied to thedisplay area DA are disposed. The pixel PX may be driven or controlledwith the various signals applied to the display area DA via the elementsor wiring in the non-display area PA.

The non-display area PA of the display panel 100 includes a bending areaBA. The bending area BA is a region where the display panel 100, andconsequently the display device, is bendable with respect to a bendingaxis. Components, elements, wirings, etc. of the display panel 100 maybe bendable at the bending area BA. The display panel 100 is bendable atthe bending area BA so that the display device which is bent disposes aportion of the non-display area PA at a rear surface of the displaypanel 100 which is opposite to a front surface thereof at which an imageis viewable, thereby reducing a dead space due to the non-display areaPA. A dead space may be defined by a portion of the non-display area PAat which signal lines, elements, wiring, etc. are omitted butnevertheless occupy a space within the display device.

Referring to FIG. 2 , the display device includes a substrate 110, athin film transistor array panel 120, an organic light emitting element125, an encapsulation layer 130, a supporting member 140, an upperprotection layer 150, and a bending area protection layer 160.

The display device and components thereof may be disposed in a planedefined by a first direction and a second direction which cross eachother. In FIG. 1 , the horizontal direction may represent one of thefirst direction and the second direction, while the vertical directionrepresents the other one of the first direction and the seconddirection. The bending axis in the bending area BA may extend along thehorizontal direction in FIG. 1 . A thickness of the display device andcomponents thereof extends along a third direction which crosses each ofthe first direction and the second direction. In FIG. 2 , the horizontaldirection may represent the first direction and/or the second direction,while the vertical direction represents a thickness direction.

The substrate 110 may include a flexible material such as plastic, whichmay be bent, curved, folded, or rolled. In an exemplary embodiment, forexample, the substrate 110 may include polyimide (“PI”), polyethylenenaphthalate (“PEN”), polycarbonate (“PC”), polyarylate (“PAR”),polyether imide (“PEI”), polyether sulfone (“PES”), etc. The substrate110 is divided into the display area DA and the non-display area PAdescribed in FIG. 1 , and the non-display area PA includes the bendingarea BA. The display area DA and the non-display area PA may define anentire planar area of the substrate 110, without being limited thereto.

The thin film transistor array panel 120 is disposed on the substrate110 in the display area DA thereof. The thin film transistor array panel120 includes at least one thin film transistor and a plurality of signallines including a plurality of gate lines, a plurality of data lines,and a plurality of driving voltage lines. The thin film transistor maybe respectively disposed in each pixel PX among a plurality of the pixelPX, and connected to a plurality of signal lines at the pixel PX.

The organic light emitting element 125 is disposed on the thin filmtransistor array panel 120. The organic light emitting element 125 maybe disposed in each pixel PX among a plurality of the pixel PX. Theorganic light emitting element 125 may include a pixel electrode, acommon electrode, and an organic emission layer. The thin filmtransistor and the pixel electrode of the thin film transistor arraypanel 120 are connected to each other such that the light emission atthe pixel PX is controlled. The pixel PX may include a light emissionarea at which light is emitted from the organic light emitting element125. Holes and electrons are injected into the organic emission layerfrom the pixel electrode and the common electrode, and an exciton, ofwhich the hole and electron are combined, is dropped from an excitedstate to a ground state, thereby realizing the light emission.

According to an exemplary embodiment, a touch sensing layer (not shown)for sensing a touch to the display device and/or the display panel 100may be further included, and may be disposed above or under the organiclight emitting element 125.

The encapsulation layer 130 covering the organic light emitting element125 is disposed on the organic light emitting element 125. Theencapsulation layer 130 covers side surface as well as an upper surfaceof the organic light emitting element 125, thereby encapsulating theorganic light emitting element 125 on the substrate 110. Since theorganic light emitting element 125 is susceptible to moisture andoxygen, the encapsulation layer 130 seals the organic light emittingelement 125 to block the inflow of external moisture and oxygen fromoutside the encapsulation layer 130.

The encapsulation layer 130 may include a plurality of layers, and maybe formed or include of a composite layer including both an inorganiclayer and an organic layer. The encapsulation layer 130 may be formed orinclude of a triple layer in which an inorganic layer, an organic layer,and an inorganic layer are sequentially provided or formed. Here, theinorganic layer may include at least one among a metal oxide, a metaloxynitride, a silicon oxide, a silicon nitride, and a siliconoxynitride. The organic layer may include or be formed of polymer seriesmaterials, without being limited thereto.

The supporting member 140 is disposed under the substrate 110, on a rearsurface of the substrate 110 opposite to the front surface on which thethin film transistor array panel 120, the organic light emitting element125 and the encapsulation layer 130 are disposed. The supporting member140 may have a function of protecting and supporting the substrate 110.The supporting member 140 may define or include an opening thereinoverlapping the bending area BA. Accordingly, the display panel may beeasily bent in the bending area BA since the supporting member 140 isnot disposed in the bending area BA.

The upper protection layer 150 is disposed on the encapsulation layer130. In an exemplary embodiment of manufacturing a display device, theupper protection layer 150 may be provided or formed by spraying anultraviolet (“UV”)-curable resin such as by an inkjet printing method,and curing the UV-curable resin with ultraviolet rays (e.g., anultraviolet ray curable resin).

The UV-curable resin may include an ultraviolet ray curable material.The ultraviolet ray curable material as a material that may be curedwith ultraviolet rays may include at least one among an acrylate-basedpolymer (e.g., a polymer including acrylate), polyurethane, and anacrylate-based material including SiO (e.g., an acrylate materialincluding SiO), without being limited thereto. The ultraviolet raycurable material may include any of a number of materials that may becured with ultraviolet rays. The UV-curable resin may further include aphotoinitiator, a heat stabilizer, an antioxidant, an antistatic agent,and/or a slip agent.

The upper protection layer 150 may include a cured portion of theabove-described ultraviolet ray curable material. That is, the upperprotection layer 150 may include at least one cured portion among theacrylate-based polymer, polyurethane, and the acrylate-based materialincluding SiO. Also, the upper protection layer 150 may further includethe photoinitiator, the heat stabilizer, the antioxidant, the antistaticagent, or the slip agent remaining in the upper protection layer 150after the UV-curable resin for forming the upper protection layer 150 iscured.

The upper protection layer 150 as a cured portion of a material layer,according to an exemplary embodiment, may include at least one among anacryl-based resin (e.g., a resin including an acryl material), a butylrubber, a vinyl acetate resin, an ethylene vinyl acetate (“EVA”) resin,a natural rubber, a nitrile, a siliceous resin, a silicon rubber, and astyrene block polymer. As further including at least one of thesematerials, the upper protection layer 150 may have predeterminedadhesiveness with respect to the encapsulation layer 130. Theadhesiveness of the upper protection layer 150 with respect to theencapsulation layer 130 may be about 3 grams-force per inch (gf/inch) toabout 10 gf/inch.

The upper protection layer 150 is removably disposed on theencapsulation layer 130. In an exemplary embodiment, the upperprotection layer 150 is disposed on the encapsulation layer 130 toprotect the encapsulation layer 130 such as during a manufacturingprocess, and is subsequently removed. The upper protection layer 150 maybe disposed along an entirety of the encapsulation layer 130 in thedisplay area DA, without being limited thereto. The upper protectionlayer 150 may be selectively disposed in some regions on theencapsulation layer 130 in the display area DA, and/or may havedifferent thicknesses per region of the encapsulation layer 130 in thedisplay area DA.

A maximum thickness of the upper protection layer 150 may be about 100micrometers (μm) to about 150 μm. The thickness of the upper protectionlayer 150 is a height in a vertical direction or thickness directionwith respect to an upper surface of the substrate 110. The thickness ofthe upper protection layer 150 may gradually decrease as a distance toan end of the upper protection layer 150 decreases. In cross-section,the upper surface of the upper protection layer 150 may have an inclinedshape that is curved at the end, and the inclination of the uppersurface of the upper protection layer 150 with respect to the substrate110 may increase as a distance to the end of the upper protection layer150 decreases.

The bending area protection layer 160 is disposed on the substrate 110in the bending area BA thereof, and is spaced apart from the upperprotection layer 150 and the encapsulation layer 130 along the substrate110, without being in contact with the upper protection layer 150 andthe encapsulation layer 130. The bending area protection layer 160covers the bending area BA and relaxes a stress force applied to wiring(not shown) disposed in the bending area BA of the substrate 110 duringthe bending of the display device, thereby reducing or effectivelypreventing cracks in the wiring especially portions thereof disposed inthe bending area BA.

In an exemplary embodiment of manufacturing a display device, thebending area protection layer 160 may be provided or formed by injectingthe UV-curable resin such as by the inkjet printing method and curingthe UV-curable resin with ultraviolet rays. The UV-curable resin mayinclude the ultraviolet ray curable material. The ultraviolet raycurable material means a material that may be cured with ultravioletrays, and the detailed contents are as described in the description ofthe upper protection layer 150.

The bending area protection layer 160 may include the cured portion ofan ultraviolet ray curable material as described in the description ofthe upper protection layer 150, and thus a detailed description thereofis omitted here. The bending area protection layer 160 may include asame material as the upper protection layer 150. The bending areaprotection layer 160 and the upper protection layer 150 may respectivelybe portions of a same material layer among layers disposed on thesubstrate 110. However, according to the exemplary embodiment, bendingarea protection layer 160 and the upper protection layer 150 may beprovided or formed to include different materials and/or respectively beportions of different material layers among layers disposed on thesubstrate 110.

The bending area protection layer 160 may further include thephotoinitiator, the heat stabilizer, the antioxidant, the antistaticagent, or the slip agent remaining in the bending area protection layer160 after the UV-curable resin for forming the bending area protectionlayer 160 is cured.

Also, the bending area protection layer 160 may further include at leastone among the acryl-based resin, the butyl rubber, the vinyl acetateresin, the ethylene vinyl acetate (“EVA”) resin, the natural rubber, thenitrile, the siliceous resin, the silicon rubber, and the styrene blockpolymer according to an exemplary embodiment. As these materials areincluded, the bending area protection layer 160 may have thepredetermined adhesiveness. The adhesiveness of the bending areaprotection layer 160 with respect to an underlying layer in contacttherewith such as the substrate 110, may be higher than the adhesivenessof the upper protection layer 150 with respect to an underlying layersuch as the encapsulation layer 130. In an exemplary embodiment, forexample, the adhesiveness of the bending area protection layer 160 maybe about 50 gf/inch to about 200 gf/inch.

A maximum thickness of the bending area protection layer 160 may be fromabout 50 μm to about 150 μm. The thickness of the bending areaprotection layer 160 is the height in the vertical direction withrespect to the upper surface of the substrate 110.

The bending area protection layer 160 may overlap a portion of thesupporting member 140 in the display area DA and a portion of thesupporting member 140 in the non-display area PA which is located beyondthe bending area BA in a direction towards an end of the display device(e.g., furthest to the right in FIG. 2 ).

A width of an overlapping region at which the bending area protectionlayer 160 and the supporting member 140 overlap each other may be about100 μm to about 200 μm. The width of the overlapping region is adistance taken in a normal direction to the bending axis, at which thebending area protection layer 160 and the supporting member 140 overlapeach other. Referring to FIG. 2 , the width is taken along thehorizontal direction, which is normal to the bending axis located in thebending area BA. That is, the bending area protection layer 160 may beextended and disposed to a region that is 100 μm to 200 μm away from thebending area BA, at each of opposing sides thereof. As such, as theportion of the bending area protection layer 160 overlaps the supportingmember 140, the cracking of the wiring disposed in the bending area BAmay be reduced or effectively prevented.

An exemplary embodiment of manufacturing method of the display device isdescribed with reference to FIG. 3 to FIG. 5 . FIG. 3 is a flowchartshowing an exemplary embodiment of a manufacturing method of a displaydevice, and FIG. 4 is a cross-sectional view of an exemplary embodimentof a display device provided according to the manufacturing method ofFIG. 3 . FIG. 5 is a cross-sectional view showing the display device ofFIG. 4 , which is bent

The substrate 110 is provided or formed on a base substrate or carriersubstrate (not shown), such as to be attached thereto. The basesubstrate and the substrate 110 may be removably attachable to eachother. On the substrate 110, the thin film transistor array panel 120and the organic light emitting element 125 are provided or formed in thedisplay area DA of the substrate 110, to each be encapsulated by theencapsulation layer 130 in the display area DA of the substrate 110. Aconductive wiring (not shown) is provided or formed in the non-displayarea PA of the substrate 110. The base substrate attached to thesubstrate 110 is to ensure a favorable overall thickness and rigidityfor handling the substrate 110 and layers provided thereon duringmanufacturing of the display device. The base substrate may be aflexible substrate.

As shown in FIG. 3 , the upper protection layer 150 and the bending areaprotection layer 160 (FIG. 2 ) are respectively provided or formed bythe inkjet printing method, in the bending area BA and on theencapsulation layer 130 in the display area DA, on the substrate 110,(S101).

For forming the upper protection layer 150 and the bending areaprotection layer 160, the UV-curable resin may be sprayed at apredetermined volume through a nozzle of an inkjet printing apparatus ata predetermined position along the substrate 110 (e.g., at the displayarea DA and at the non-display area PA), and cured with ultraviolet(“UV”) rays.

In a conventional flexible organic light emitting device, anencapsulation layer is provided or formed to encapsulate a displaysubstrate to reduce or effectively prevent penetration of moisture andoxygen to the organic material as a light emitting material. However,the encapsulation layer of the conventional flexible organic lightemitting device is relatively easily damaged by external scratches, orstampings or scratches due to foreign materials generated duringsubsequent manufacturing processes, and these stampings or scratchescause defects such as dark spots, etc. of the conventional flexibleorganic light emitting device.

To solve these problems, for the substrate of the conventional flexibleorganic light emitting device, an upper protection film including orformed of a polyethylene terephthalate (“PET”) film is attached to theencapsulation layer so as to protect the encapsulation layer during thesubsequent manufacturing processes. However, the process of attachingthe upper protection film is additionally used to manufacture theconventional flexible organic light emitting device, which reducesproductivity and yield for the manufactured conventional flexibleorganic light emitting device. Furthermore, selective coating is notpossible for individual portions of the upper protection layer, sincethe upper protection layer may only be provided or formed on an entiretyof the surface of the substrate having the encapsulation layer thereon.

However, according to one or more exemplary embodiment, the upperprotection layer 150 and the bending area protection layer 160 may beprovided or formed simultaneously, thereby simplifying the process. Asbeing provided or formed simultaneously, the upper protection layer 150and the bending area protection layer 160 may be provided in or formedfrom as same process and/or using a same material layer, such that theupper protection layer 150 and the bending area protection layer 160 ofthe display device are respectively portions of the same material layer.Also, since the upper protection layer 150 may be locally provided orformed only in some regions by the inkjet printing method, as opposed tobe provided at an entirety of a substrate of the conventional displaypanel, a material cost may be reduced. That is, the upper protectionlayer 150 may be provided or formed only at the region where theencapsulation layer 130 of the display panel is disposed, instead ofproviding or forming the upper protection layer 150 on an entirety ofthe substrate of the conventional display panel.

The spraying and curing process of the UV-curable resin for providing orforming the upper protection layer 150 on the encapsulation layer 130may be repeatedly performed several times. Specifically, an individualprocess of injecting the UV-curable resin onto the substrate 110 at theregion where the upper protection layer 150 is to be provided or formed,with a thickness of about 10 μm to about 20 μm and curing the injectedUV-curable resin from the individual process with ultraviolet rays, isrepeated several times to increase the thickness of the cured UV-resinto provide or form the upper protection layer 150 at a total thicknessof about 100 μm to about 150 μm. That is, in an exemplary embodiment, anindividual layer of the UV-curable resin having a thickness of about 10μm to about 20 μm is provided and cured, multiple times, to provide theupper protection layer 150 having the maximum thickness of about 100 μmto about 150 μm. If a relatively large amount of UV-curable resin iscured at one time, the curing time increases and all portions of theUV-curable resin may not be uniformly cured. However, in an exemplaryembodiment the UV-curable resin sprayed in an individual process at thethickness of about 100 μm to about 150 μm may be cured at one time inone individual process.

For providing or forming the bending area protection layer 160 in thebending area BA, the UV-curable resin may be injected and cured to beprovided or formed with the thickness of about 50 μm to about 150 μmalong a region disposed in the bending area BA and which extends fromthe bending area BA by about 100 μm to about 200 μm. That is, a totalwidth of the bending area protection layer 160 may include a width ofthe bending area BA in addition to both distances which are eachextended from opposing sides of the bending area BA by about 100 μm toabout 200 μm. As such, the bending area protection layer 160 whichextends from the bending area BA and toward the display area DA, isprovided or formed to not overlap the encapsulation layer 130 and theupper protection layer 150.

As described above, the UV-curable resin may contain the ultraviolet raycurable material, and the detailed description is the same as describedin FIG. 2 such that repeated description is omitted here.

The base substrate is removed from the substrate 110 having the upperprotection layer 150 and the bending area protection layer 160 on thethin film transistor array panel 120 and the organic light emittingelement 125 which are encapsulated by the encapsulation layer 130thereon, and the supporting member 140 is attached under the substrate110 having the base substrate removed therefrom (S102). The supportingmember 140 may serve to support and protect the substrate 110,especially as having the various layers provided or formed thereon. Thesupporting member 140 may form an outermost layer of the display device,without being limited thereto.

Portions of the supporting member 140 may be spaced apart from eachother to define the opening in the supporting member 140 which overlapsthe bending area BA. A width of each portion of the supporting member140 which overlaps the bending area protection layer 160 may be about100 μm to about 200 μm along the substrate 110 in a direction normal tothe bending axis.

After attaching the supporting member 140, a driving integrated circuitchip 200 may be provided or formed on an end portion of the substrate110 in the non-display area PA thereof. Along the substrate 110, thedriving integrated circuit chip 200 on the end portion of the substrate110 may be disposed to be spaced apart from the bending area protectionlayer 160 covering the bending area BA without being in contacttherewith. The driving integrated circuit chip 200 may control thedisplay device and output signals for driving the display panel 100 ofthe display device. The driving integrated circuit chip 200 may be anintegral driving integrated circuit chip that applies a timing signal toapply a data voltage to a pixel PX, a gate voltage to a pixel PX, or thelike, without being limited thereto.

The upper protection layer 150 is removed from the substrate 110, and isparticularly removed from the encapsulation layer 130 on the substrate110 (S103). The removing of the upper protection layer 150 exposes theencapsulation layer 130 on the substrate 110. The upper protection layer150 may be removed by a physical method such as including attached anadhesive member (e.g., tape) to one end and peeling the adhesive memberand the upper protection layer 150 attached thereto by external force,but is not limited thereto. Since the bending area protection layer 160is provided or formed to not be in contact with the upper protectionlayer 150 and the encapsulation layer 130, only the upper protectionlayer 150 may be removed without removing the bending area protectionlayer 160. That is, the bending area protection layer 160 may remain onthe substrate 110 having the various layers provided or formed thereon,after the upper protection layer 150 is removed.

The adhesiveness of the upper protection layer 150 with respect to theencapsulation layer 130 may be lower than the adhesiveness of thebending area protection layer 160 with respect to the substrate 110. Inan exemplary embodiment, for example, the adhesiveness of the upperprotection layer 150 with respect to an underlying layer in contacttherewith may be about 3 gf/inch to about 10 gf/inch, and theadhesiveness of the bending area protection layer 160 with respect to anunderlying layer in contact therewith may be about 50 gf/inch to about200 gf/inch.

Since the upper protection layer 150 is removably attachable to theencapsulation layer 130, such that the upper protection layer 150 isattachable during some processes of manufacturing and removablesubsequent to the processes, upper and lower limits of the adhesivenessare defined. If the adhesiveness of the upper protection layer 150 withrespect to an underlying layer in contact therewith such as theencapsulation layer 130 is less than 3 gf/inch, there may be aphenomenon in that the upper protection layer 150 is prematurely peeledoff or the outer portion falls off during the process. In contrast, ifthe adhesiveness of the upper protection layer 150 with respect to anunderlying layer in contact therewith such as the encapsulation layer130 exceeds 10 gf/inch, the encapsulation layer 130 is damaged when theupper protection layer 150 is removed.

Unlike the upper protection layer 150, which is removed after someprocesses of manufacturing, the bending area protection layer 160 whichis removably attachable to an underlying layer in contact therewith suchas the substrate 110 is not removed and remains on the substrate 110 torelieve the stress applied to the substrate 110 during bending of thedisplay panel 100 and/or the display device. Therefore, if theadhesiveness described above of the bending area protection layer 160 isless than about 50 gf/inch, the bending area protection layer 160 may betorn and damaged.

After the upper protection layer 150 is removed, a polarization film170, an adhesive layer 180, and a window panel 190 are sequentiallyprovided or formed on the substrate 110 having the various layersthereon (S104).

The polarization film 170 may reduce the reflection of external lightincident from outside the display device. When the external light passesthrough the polarization film 170 and is reflected by the thin filmtransistor array panel 120 and then passes through the polarization film170 again, the phase of the external light may be changed. As a result,extinction interference occurs between the phase of the reflected lightand the external light incident to the polarization film 170, so thatthe light recognizable from outside the display device may be suppressedand the display quality of the display device may be improved. Also, asa retarder (not shown) is further included, the reflection of externallight is suppressed by reducing or effectively preventing external lightpassing through the retarder and the polarization film 170 from beingreflected by the thin film transistor array panel 120 and returnedthrough the polarization film 170. However, the invention is notlimited, and the polarization film 170 may include any conventionalconfiguration capable of reducing external light reflection.

The adhesive layer 180 may include an optically clear adhesive (“OCA”),an optically clear resin (“OCR”), and/or a pressure sensitive adhesive(“PSA”).

The window panel 190 serves to protect the display panel 100 and/or thedisplay device from an environment outside thereof. The window panel 190may form an outermost layer of the display panel 100 and/or the displaydevice. The image output from the display panel 100 may be transmittedto the user through the window panel 190. The window panel 190 mayinclude or be formed of a light transmissive material, such as glass,polyethylene terephthalate, and acryl, but is not limited thereto. Thus,the display device shown in FIG. 4 is manufactured.

FIG. 4 is the cross-sectional view of the display device provided orformed according to the manufacturing method of FIG. 3 . In FIG. 4 , thedisplay device including the substrate 110 having the various layersthereon, is flat. The display device which is flat, disposes thenon-display area PA adjacent to the display area DA along the substrate110, and disposes the substrate 110 and the elements or wiring in thebending area BA of the substrate 110 flat.

The display device of FIG. 4 is similar to the display device of FIG. 2except for including the polarization film 170, the adhesive layer 180,the window panel 190, and a driving integrated circuit chip 200 andexcluding the upper protection layer 150, such that the detaileddescription of the overlapped contents is omitted.

The display device of FIG. 4 does not include the upper protection layer150 shown in FIG. 2 , by the manufacturing process of removing the upperprotection layer 150 of FIG. 3 (S103) and subsequently attaching thepolarization film 170, the adhesive layer 180, and the window panel 190on the encapsulation layer 130 (S104). The removal of the upperprotection layer 150 from the encapsulation layer 130 (S103) disposes anupper surface of the encapsulation layer 130 exposed to outside theencapsulation layer 130. The attaching of the polarization film 170disposes the polarization film 170 on the upper surface of theencapsulation layer 130 which is exposed to outside thereof by theremoval of the upper protection layer 150.

Along the substrate 110, the driving integrated circuit chip 200 isdisposed to be spaced apart from the bending area protection layer 160in the non-display area PA of the substrate 110. The display device ofFIG. 4 may further include a printed circuit board (“PCB”) (not shown)attached to the display panel 100. The printed circuit board (“PCB”) maybe attached to the display panel 100 through the driving integratedcircuit chip 200, without being limited thereto. The printed circuitboard (“PCB”) may provide control signals or driving signals with whichthe display panel (e.g., the pixel PX) is controlled and/or imagesignals or data signals including information for the image to bedisplayed by the pixel PX, to the driving integrated circuit chip 200from outside thereof.

The details of the polarization film 170, the adhesive layer 180, thewindow panel 190, and the driving integrated circuit chip 200 are thesame as those described with respect to FIG. 3 and are omitted here.According to an exemplary embodiment, another adhesive layer may beincluded between the encapsulation layer 130 and the polarization film170, without being limited thereto.

Referring to FIG. 5 , the display panel of FIG. 4 is bent at the bendingarea BA. The display panel 100 which is bent disposes the drivingintegrated circuit chip 200 to overlap the display area DA of thedisplay panel 100. When the display panel 100 is bent, the wiringdisposed in the bending area BA may be stressed, but the bending areaprotection layer 160 covering the bending area BA and the wiringdisposed therein receives a stress (e.g., tensile stress) when bendingsuch that the stress applied to the wiring may be reduced.

FIG. 6 is a top plan view showing an exemplary embodiment of an uppersurface of an encapsulation layer of a display device. Specifically,FIG. 6 represents the upper surface of the encapsulation layer 130 afterthe upper protection layer 150 (FIG. 2 ) is removed. Therefore, thebending area protection layer 160 is disposed in the bending area BA,but the upper protection layer 150 is removed and is not present.

As described above, the upper protection layer 150 and the bending areaprotection layer 160 of the display device according to one or moreexemplary embodiment are each formed by a process of injecting theUV-curable resin by the inkjet printing method and curing the injectedUV-curable resin with ultraviolet rays. When the upper protection layer150 is provided or formed by the inkjet printing method on theencapsulation layer 130, a nano structure 135 including nano sizedprotrusions and depressions is formed at an edge region where an end ofthe upper protection layer 150 is disposed overlapping the encapsulationlayer 130. In an exemplary embodiment, the nano structure 135 may beportions of the encapsulation layer 130 which have been deformed due toremoval of the upper protection layer 150. In an exemplary embodiment,removal of the upper protection layer 150 from the upper surface of theencapsulation layer 130 forms the nano structure 135 defined by nanosized protrusions and depressions of the upper surface. As the nanostructure 135 includes a protrusions and depressions of a nano-unit, anafterimage of a bright-banded shape may be seen compared with otherregions.

According to an exemplary embodiment, the upper protection layer 150 maybe selectively provided or formed along the substrate 110 (e.g., only onthe encapsulation layer 130) and removed from the encapsulation layer130 of each display panel 100, instead of forming the upper protectionlayer 150 on an entirety of the substrate 110. Where the upperprotection layer 150 is selectively provided or formed along thesubstrate 110 (e.g., only on the encapsulation layer 130) and removedfrom the encapsulation layer 130 of each display panel 100, the nanostructure 135 may be disposed in a closed line shape respectivelyextending along lengths of edges of the encapsulation layer 130 in thetop plan view.

Another exemplary embodiment of a display device is described withreference to FIG. 7 .

FIG. 7 is a cross-sectional view of another exemplary embodiment of adisplay device. The display device of FIG. 7 is similar to the exemplaryembodiment of FIG. 2 except for further including a first adhesivesupporting layer 155 such that the detailed description of the sameconstituent elements is omitted, and differences are explained.

The display device according to the exemplary embodiment of FIG. 7further includes the first adhesive supporting layer 155 between theencapsulation layer 130 and the upper protection layer 150. Theadhesiveness of the first adhesive supporting layer 155 with respect toan underlying layer in contact therewith such as the encapsulation layer130 may be lower than the adhesiveness of the bending area protectionlayer 160 with respect to an underlying layer such as the substrate 110.In an exemplary embodiment, for example, the adhesiveness of the firstadhesive supporting layer 155 may be about 3 gf/inch to about 10gf/inch.

The first adhesive supporting layer 155 may include at least one amongthe acryl-based resin, the butyl rubber, the vinyl acetate resin, theethylene vinyl acetate (“EVA”) resin, the natural rubber, the nitrile,the siliceous resin, the silicon rubber, and the styrene block polymeraccording to an exemplary embodiment.

If the first adhesive supporting layer 155 is further included, properadhesiveness of the first adhesive supporting layer 155 with theencapsulation layer 130 may be maintained regardless of the adhesivenessof the upper protection layer 150 with respect to an underlying layer incontact therewith. That is, even if the adhesiveness of the upperprotection layer 150 is not sufficiently low to facilitate removalthereof from the underlying layer in contact therewith such as theencapsulation layer 130, the upper protection layer 150 may be removedfrom the encapsulation layer 130 together with the first adhesivesupporting layer 155 without damaging the encapsulation layer 130.

Another exemplary embodiment of a display device is described withreference to FIG. 8 . FIG. 8 is a cross-sectional view of still anotherexemplary embodiment of a display device. Since the display device ofFIG. 8 is similar to the exemplary embodiment of FIG. 2 except forincluding a second adhesive supporting layer 165, the detaileddescription of the same constituent elements is omitted, and differencesare explained.

The display device according to the exemplary embodiment of FIG. 8further includes a second adhesive supporting layer 165 between thesubstrate 110 and the bending area protection layer 160. Theadhesiveness of the second adhesive supporting layer 165 with respect toan underlying layer in contact therewith in contact therewith such asthe substrate 110 may be greater than the adhesiveness of the upperprotection layer 150 with respect to an underlying layer in contacttherewith such as the encapsulation layer 130. In an exemplaryembodiment, for example, the adhesiveness of the second adhesivesupporting layer 165 may be about 50 gf/inch to about 200 gf/inch.

The second adhesive supporting layer 165 may further include at leastamong of the acryl-based resin, the butyl rubber, the vinyl acetateresin, the ethylene vinyl acetate (“EVA”) resin, the natural rubber, thenitrile, the siliceous resin, the silicon rubber, and the styrene blockpolymer according to an exemplary embodiment.

If the second adhesive supporting layer 165 is further included, even ifthe adhesiveness of the bending area protection layer 160 is not highenough to remain attached to substrate 110, the second adhesivesupporting layer 165 may maintain the attached state of the bending areaprotection layer 160 on the substrate 110 without removal or peeling ofthe bending area protection layer 160 from the substrate 110.

An example of the formation of the upper protection layer 150 on theencapsulation layer 130 according to an exemplary embodiment will now bedescribed. FIG. 9 is an image of an exemplary embodiment of an upperprotection layer 150 removably disposed on an encapsulation layer 130 ofa display device.

As shown in FIG. 9 the upper protection layer 150 may be provided orformed on the encapsulation layer 130 to have a total thickness of about100 μm to about 150 μm by performing an individual process of sprayingand curing a layer of UV-curable resin applied by the inkjet printingmethod to the encapsulation layer 130, several times.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A display device comprising: a substrateincluding a bending area at which the display device is bendable; anorganic light emitting element disposed on the substrate; and anencapsulation layer covering an upper surface and a side surface of theorganic light emitting element, wherein at least a portion of an uppersurface of the encapsulation layer includes a nano structure defined bynano sized protrusions and depressions of the upper surface.
 2. Thedisplay device of claim 1, wherein in a top plan view, the nanostructure forms a closed line shape extended along edges of theencapsulation layer.
 3. The display device of claim 2, furthercomprising: a bending area protection layer covering the bending area ofthe substrate, wherein along the substrate, the bending area protectionlayer is disposed separated from the encapsulation layer, and whereinthe bending area protection layer includes a cured portion of anultraviolet ray curable material.
 4. The display device of claim 3,wherein the ultraviolet ray curable material includes at least one amonga polymer including acrylate, polyurethane, and an acrylate materialincluding SiO.
 5. The display device of claim 4, wherein the ultravioletray curable material includes at least one among a resin including anacryl-material, a butyl rubber, a vinyl acetate resin, an ethylene vinylacetate resin, a natural rubber, a nitrile, a siliceous resin, a siliconrubber, and a styrene block polymer.
 6. The display device of claim 5,wherein adhesiveness of the bending area protection layer is about 50grams-force per inch to about 200 grams-force per inch.
 7. The displaydevice of claim 6, wherein a maximum thickness of the bending areaprotection layer is about 50 micrometers to about 150 micrometers. 8.The display device of claim 7, further comprising a supporting memberdisposed on a rear surface of the substrate, wherein the organic lightemitting element and the encapsulation layer are disposed on a frontsurface of the substrate which is opposite to the rear surface thereof,and the supporting member defines an opening therein which overlaps thebending area.
 9. The display device of claim 8, wherein along thesubstrate, the supporting member defining the opening which overlaps thebending area, overlaps the bending area protection layer covering thebending area, by about 100 micrometers to about 200 micrometers.
 10. Thedisplay device of claim 6, further comprising a driving integratedcircuit chip disposed on an end portion of the substrate, wherein alongthe substrate, the bending area protection layer covering the bendingarea is disposed separated from the driving integrated circuit chipdisposed on the end portion of the substrate.
 11. The display device ofclaim 10, further comprising: an upper protection layer removablyattachable to the encapsulation layer, wherein removal of a portion ofthe upper protection layer from the encapsulation layer disposes theupper surface of the encapsulation layer exposed to outside theencapsulation layer and forms the nano structure; a polarization filmdisposed on the upper surface of the encapsulation layer which isexposed to outside the encapsulation layer; and a window panel disposedon the polarization film.
 12. The display device of claim 3, furthercomprising at the bending area of the substrate, an adhesive supportinglayer disposed between the substrate and the bending area protectionlayer and with which the substrate is attached to the bending areaprotection layer.
 13. The display device of claim 12, wherein theadhesive supporting layer includes at least one among a resin includingan acryl material, a butyl rubber, a vinyl acetate resin, an ethylenevinyl acetate resin, a natural rubber, a nitrile, a siliceous resin, asilicon rubber, and a styrene block polymer.
 14. The display device ofclaim 13, wherein adhesiveness of the adhesive supporting layer ishigher than adhesiveness of the bending area protection layer.